Primary document guiding all military services in their interactions with religion.

Of note, from paragraph 4.b:

“Unless it could have an adverse impact on military readiness, unit cohesion, and good order and discipline, the Military Departments will accommodate individual expressions of sincerely held beliefs (conscience, moral principles, or religious beliefs) of Service members in accordance with the policies and procedures in this instruction.”

Continues the educational and ecclesiastical requirements for appointing military
chaplains.

From Section 4:

It is DoD policy that the Chaplaincies of the Military Departments:

4.1. Are established to advise and assist commanders in the discharge of their
responsibilities to provide for the free exercise of religion in the context of military service as guaranteed by the Constitution, to assist commanders in managing Religious Affairs, and to serve as the principal advisors to commanders for all issues regarding the impact of religion on military operations…

Sets doctrine and guidance for US Armed Forces regarding joint force religious support

“US military chaplains represent specific religious organizations and work together within the pluralistic context of the military to ensure freedom of religion within the joint force…

Military commanders are responsible to provide for the free exercise of religion of those under their authority as directed by Joint Publication (JP) 1, Doctrine for the Armed Forces of the United States.”